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Collins R-392?

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mfn002

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Has anyone ever played around with one of these? I just got one yesterday, and would be interested as to what people think of this.
 

jim202

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Has anyone ever played around with one of these? I just got one yesterday, and would be interested as to what people think of this.
Those use to be the work horse of many government agencies at radio sites. They are big, heavy and generate heat. The internals are a whole bunch of mechanical gears and shafts. Did I mention they generate heat from the TUBES inside. Those are those glass bottles with the funny glow from inside them. They use high voltage in the range of about 300 volts or so if I remember correctly. No they won't work off the car battery.

Think there were 2 antenna connectors on the rear. Think one was a BNC and the other may have been an HN. Kind of remember needing an adapter to make the connection to the coax cable.

They had a mechanical digital frequency readout to indicate where the receiver was set to.

If you do a search on the Internet, you might just get lucky and find a manual for those radios. Think I remember that t hey used spline set screws and not the standard Allan screws we normally see.

Just how well the receiver works will depend on who had it last and how well they took care of it. I would expect to find the filter caps in the power supply to be all dried out. So if you plug it in and don't get a loud bang from one of the caps blowing up, you will probably have hum in the audio output. You will need an external speaker connected to the terminal strip on the rear.

Have fun with it.
 
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An excelllent HF receiver, they were designed to tune to a specific frequency and not for a lot of general SWL tuning, there was a term "390 wrist" for operators that were required to monitpr a span of frequencies.
 

mfn002

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Apparently, the unit's last owner did some modifications to it. It seems that the two multi-pin audio jacks were removed and replaced by standard RCA mono plugs. It also has numerous issues:
-The "DIAL LOCK" switch is missing
-The "DIAL ZERO" switch appears to be hopelessly jammed
-The dial light control switch's "DIM" function is gone (the light's either on or off)
-The bandwidth selector seems to do absolutely nothing
-The "STANDBY" position on the power selector switch seems to make the thing flicker on and off at random

I have yet to receive any broadcasts--or anything, for that matter--on it. All I've been getting so far is static, which seems to get louder when the BFO is turned on. It also doesn't seem to make any difference if I have an antenna hooked up to it or not. I did notice that when an antenna is hooked up, there is a static burst when I jiggle it around and the antenna contacts something metal. I did look inside, and, as far as I can tell, all tubes are glowing when the power is on. It's remarkably clean in there, and all of the internal components appear original. There's a slight correction: It's not a Collins unit, but one manufactured by Dubrow Electronic Industries. The name plate says:
RECEIVER, RADIO R-392/URR
SERIAL NO. 59
DUBROW ELECTRONIC INDUSTRIES, INC.
ORDER NO. 52713-PP-61
U.S.
It uses 24-28 VDC at 3 or 5 amps (I'm running it off of a 24VDC power supply putting out 6.5 amps).
 
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mfn002

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Do you know what kind of BNC antenna I can hook up to this? Also, since mine seems to have weak RX, would some sort of preamp fix that?
 

W2NJS

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First of all, there is no such thing as "weak RX" on a radio of this type. Your radio sounds as if it needs a good mechanical and electrical going over and tuneup. It's a very good bet that your radio has at least some tubes that need replacing, as well as capacitors that are out of spec. Getting a good manual, as I suggested above, would certainly be a good first step. Also, if you were to do a Google search for references to the R series radios I'm sure, the internet being what it is, that you'd find a wealth of material to help you. Here is one you could start with:

Rovero's R-392 Page

There appear to be about 25,999 other similar references on Google.
 

mfn002

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What I'm really wondering about is why hooking up an antenna seems to do nothing. When I took it out of the case, I noticed that whacking the side panel next where the antenna connectors are seemed to make some difference, and the antenna started working. I checked the connections, and it appears that at some point the lead wire for the wire antenna connector broke off, and the BNC connector's lead wire was connected with a twist connector to the wire antenna connector's lead wire, which goes to some sort of relay. I played around with the wires, and it seemed to make no difference with the reception, although on occasion there are bursts of louder static. Also, sometimes the audio doesn't work right. It comes out as very faint hiss with no real static, and I have to turn the volume all the way up in order to hear anything (I know tubes need to warm up, but this continues for several minutes). When that happens, the squelch function stops working, and I only hear a "pop" when any of the switches are turned.

As I said before, all the tubes I could see heat up and glow as they should. Keep in mind that this is the first time I have ever played around with a tube radio, so my knowledge about these things is fairly limited.
 
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W2NJS

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If you insist on trying to fix the radio without any relevant data at hand you're probably just wasting your time, more so if you're not familiar with the theory of operation of receivers. Get some data, get some help, and stop wasting your time hitting the radio to make it work. Have you looked at any of the R390/392 help sites yet? Have you looked at the Fair Radio site to see if they have a manual for the radio?
 

mfn002

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I found a Field and Depot Repair Manual on eBay, so I'll probably get that. What I'm trying to get at is if there is a single component or something that may be causing the problem. Sure, the manual will tell me how it works and what controls what, but it won't tell me what component might be broken or out of alignment. I suspect that, because several functions aren't working correctly, that it might be more than one component. If that's the case, it'll take me weeks, if not months or even years, to find the necessary replacement components when I finally do identify the source of the problem.

UPDATE: I have narrowed the problem down to either the RF or audio sections. I noticed that I can actually hear the sound of the switch I am moving in my headphones. This seems to be most noticable with the BFO power switch, and somewhat noticable with all of the other audio controls. As for the RF portion, I was just listening to it, and there was a pop in my headphones and the low humming stopped and I started getting regular static, but still no response from the antenna. Whatever is causing this problem, it seems to have turned the audio section into a microphone (when I had it open yesterday with the power on, I noticed I could hear the tapping sound caused by me lightly tapping on a part of the frame).
 
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k9rzz

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You've already documented more than one problem with the radio, so why would there be just one problem causing poor reception?

I know this is a lost art, but this goes back to tube type TVs from your dad or grandpa ... CHECK THE TUBES.

Replace any bad ones.

Where do you go to check tubes in this day and age? Got me, but that's your first task.

Then you know you've got that behind you and you can go from there ... methodically.

It's a great radio. Good luck!
 
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mfn002

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I might as well go ahead and replace as many of the tubes as I can find replacements for, just to be sure. Unfortunately, the tube removal tools are missing. I did notice that they were all glowing and got warm to the touch.
 

k9rzz

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Atta boy. Search the web and you should find plenty of help getting that old girl in good running condition again in no time. There's lots of knowledgable guys out there who work with those radios on a regular basis.
 

mfn002

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I just thought of something. Depending on which specification I look at, it says the power input is either 24 or 28 volts. Even the manuals seem a little ambiguous as to what the voltage input is, with some pages saying 24 volts and others saying 28. Should it be 28? It just occurred to me because I noticed that my 24 VDC 6.5 amp power supply got very hot when I had the radio on. Although this might have something to do with the problem, in my world, the simplest solution is usually NEVER the actual solution. :roll:
 

ka3jjz

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Likely as not that supply just isn't supplying enough current - it's not always about the voltages. A small difference like that shouldn't make your power supply get all that hot...

Mike
 

mfn002

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The specs say 3 amps, and, as in my post, my power supply puts out 6.5. It doesn't usually get that hot when I'm using it for anything else.

I also have another question: will a tube still glow even if it's bad?
 

mfn002

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This is odd...
I decided to remove both side panels and pulled out every tube to see if any were burnt out (I didn't see any). I put them back in, reassembled the radio, and turned it back on. Lo and behold, there was a burst of static every time I touched the antenna. Now, I notice that the static tone and pitch change every time I change the MHz band. Unfortunately, I have yet to hear a single voice.

Also, during my inspection, I discovered that all of the tubes were from different manufacturers, so at some point someone had replaced the original ones.
 
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